Thursday 18 December
last updated 18/0006 UT
Solar activity was High yesterday with several M-class flares occurring from active regions 2241 and 2242. The largest flare was an M8.7/2B from active region 2242 (S18W02), peaking at 17/0451 UT. This flare was associated with a CME observed on LASCO C2 imagery first at 0512UT, 17 December. The CME is expected to be hit the Earth in the middle of the UT day, 19 December, though the majority of the mass is expected to pass south of Earth. Both regions have grown over the past 24 hours. Expect Moderate to High solar activity over the next 3 days. Note there is a low to moderate chance for X-class flares. The solar wind speed is expected to be light until the arrival of the CME. Geomagnetic conditions at quiet levels today, however should turn active on 19 December. Note there is a possibility of aurora being observed in southern latitudes such as Tasmania on 19-20 December. Short-wave radio fadeouts likely. High-frequency radio communications normal at this time.

Update: Expect moderate to high solar activity. A CME is expected to arrive at Earth today, 21 December. There is a possibility of aurora being observed in southern latitudes such as Tasmania at local night time hours on 21 and 22 December. An X-class flare occurred at 0027UT on 20 December and is expected to have a glancing blow at Earth on 22 December. The solar wind is presently light, but expected to increase to moderate after impact. Short-wave radio fadeouts likely. High-frequency radio communications normal at this time. http://www.ips.gov.au/